Posted 07 June 2012 - 10:01 AM
I have a problem with backscatter between my camera and my target. I have the strobes set up wide to reduce backscatter, but for my wider-angle shots (e.g., wrecks), I have a ton of backscatter still. I generally shoot ISO100, around F6.3, and around 1/200
I have an S95 with Ikelite housing as well as two YS-01 strobes.
For the Ikelite housing, would you recommend black tape on the inside and over the front of the fiber-optic sensor? Could light getting through the front be the cause of backscatter? Do you have any example of taping done with this type of Ikelite housing?
Posted 07 June 2012 - 11:10 AM
Indeed, if your on-camera flash is not blocked then it will indeed give you horrid backscatter, no matter where you place your external strobes. Its simple to test, just turn the external strobes off.
Posting a pic of your backscatter could help - basically if there's really large OOF (out of focus) blobs in the image, its likely a particle very close to the lens and you're somehow getting light right in front of the lens.
Of course visibility is a massive factor, with backscatter nearly impossible to avoid in mid-poor vis.
Strobe positioning is another factor, and people often point their strobes out slightly to light the subject with the edge of the beam, avoiding too much light hitting the water between the lens and subject. I started out with my strobes spaced far apart (for wide angle work) for the same reason, and much of the school of thought a few years ago was based on this principle. However, I find myself more often now keeping the strobes closer to the housing and pointing them outwards slightly. For example, if you space your strobes far out, but then have to point them inwards to light the subject, you'll still get backscatter. Granted the backscatter will be more side-lit and may not be as prominent. Its worth experimenting with and in the age of instant photo review, is easy to test in a few minutes (or perhaps worth a whole dive) UW.
Hope that helps. Cheers,
Posted 07 June 2012 - 06:07 PM
The basic concept is to not light any of the water between your camera and your subject. You want to catch your subject with the edge of your strobe's beam.
How to do this is a subject of endless debate. One thing to consider is that even if you feather your strobes out so the beam just catches the subject, you might get a hot spot in your photo if the strobe is too close to the camera.
Life is a beach and then you dive.
Posted 08 June 2012 - 03:11 AM
Hi, I have a problem with backscatter between my camera and my target. I have the strobes set up wide to reduce backscatter, but for my wider-angle shots (e.g., wrecks), I have a ton of backscatter still. I generally shoot ISO100, around F6.3, and around 1/200 I have an S95 with Ikelite housing as well as two YS-01 strobes. For the Ikelite housing, would you recommend black tape on the inside and over the front of the fiber-optic sensor? Could light getting through the front be the cause of backscatter? Do you have any example of taping done with this type of Ikelite housing? Thanks!
I have to wonder:
1 - How close you are to the wide angle subject?
2 - Have you dry tested the flash?
With respect to 1, if you are more than 6 feet away from your subject I would expect backscatter, even in the most optimal conditions it can be really tough to get the light on just the subject under those conditions.
With respect to 2, using a red light for focusing, and take a test shot with just the housing and camera and see if you get any illumination from the flash, that will tell you how much light is getting through.
Edited by steviet, 08 June 2012 - 03:12 AM.
Posted 08 June 2012 - 08:37 AM
The reef photo is obviously more than 6+ feet away, so there is inevitable backscatter. However, it's an obscene amount, and I know it can likely be reduced.
The squid photo is less than 5ft away, yet there's tons of backscatter. This type of backscatter is the type of backscatter I usually get (except maybe more).
Does it look like the light from the camera flash is getting through?
Posted 09 June 2012 - 03:47 AM
For the second one getting closer so as to fill the frame would be my suggestion. I always shoot RAW as it was one of the reasons I bought an S95.
Posted 09 June 2012 - 07:08 AM
That you still have backscatter suggest that the strobes are not lighting the subject, but instead the water in front or in back of the subject.
I think you need to practice your strobe placement. It appears you may have turned down the strobe power to try to avoid the backscatter. I think that was the wrong approach in these photos. The subjects need more light.
It just takes practice and experimentation. That's the beauty of digital photography. You can take all the shots you want and not run out of film.
Once you do better with the still subjects you will find it easier to get the moving ones.
Life is a beach and then you dive.
Posted 09 June 2012 - 07:13 AM
Posted 09 June 2012 - 03:42 PM
At the risk of sounding rude, neither image works because the subjects are too far away. The first, and most important, way to avoid backscatter is to get close. The next is to put the strobe in the right place, pointing in the right direction. Martin Edge, in "The Underwater Photographer", explains it best.
Don't worry about sounding rude; I'm open to criticism. These clearly are not good shots, but they are a good example of the type of backscatter that I see sometimes.
Also, by turning up the strobe power, a lot of lighter-colored subjects become overexposed. If you look at the squid, its eyes are extremely bright due to the reflection of the strobe light. Is there a way I can work around that?
Edited by Scuba_Doo, 09 June 2012 - 03:43 PM.
Posted 09 June 2012 - 03:47 PM
Olympus E-520, TLC arms, Inon Z-240s, 50mm, 14-42mm woody's diopter
Posted 10 June 2012 - 07:25 AM
Posted 10 June 2012 - 07:55 PM
I'm still quite new to this and I've never really experimented on the surface with cameras in manual mode, so underwater is where I'm learning. Hope to see significant improvements with my photos.
Edited by Scuba_Doo, 10 June 2012 - 07:55 PM.
Posted 10 June 2012 - 08:04 PM
Posted 16 June 2012 - 09:59 AM
black duct tape works great, and can be put over the outside, so you can still figure a way to feed the fiber optics.
Show us a pic of your housing setup.
nikon n90s/ikelite housing/twin SS-200 canon G2/ikelite/DS-50/optical TTL slave
sony V3/ikelite/DS-51/Heinrich DA2 slave
Posted 10 July 2012 - 12:58 PM
As someone above mentioned, get closer- there is no substitute for this.
Edited by tdtaylor, 10 July 2012 - 12:59 PM.